UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity.

It's true that compared with the scene when Unix started, today the ecological niches are fairly full, and fresh new OS ideas are harder to come by, or at least to propagate.

Some consider UNIX to be the second most important invention to come out of AT&T Bell Labs after the transistor.

The True-GNU philosophy is more extreme than I care for, but it certainly laid a foundation for the current scene, as well as providing real software.

The number of UNIX installations has grown to 10, with more expected.

My work was fairly theoretical. It was in recursive function theory. And in particular, hierarchies of functions in terms of computational complexity. I got involved in real computers and programming mainly by being - well, I was interested even as I came to graduate school.

C++ and Java, say, are presumably growing faster than plain C, but I bet C will still be around.